1. Field of the Invention
This invention relates to a releasable separate member latching device for applications such as a portable hand tool, and more specifically to a releasable guard member latching device for a portable hand tool which automatically relatches the guard member in a guarding position when the guard member returns to the guarding position after a cutting operation.
2. Description of the Prior Art
In a portable hand tool, such as a circular power saw, in which a power driven rotary saw blade performs a cutting or sawing operation on an article, such as a board, it is standard practice to provide a guard member for the rotary saw blade to prevent an operator or other person from becoming injured by the rotating saw blade as a result of coming in contact therewith. The guard member is needed for this purpose even when the saw is not operating, because of the sharpness of the teeth of the saw blade. Further, the guard member becomes particularly important when the saw is in operation, because of the high rate of speed at which the saw blade rotates, in order to prevent serious injury to the operator during a sawing operation.
More specifically, in known circular power saws the guard member is journaled on a housing portion for a rotatable drive shaft on which the saw blade is mounted for a sawing operation. The guard member is biased into a guarding position by a relatively strong coil spring, to prevent the operator from inadvertently engaging the rotary saw blade both when the saw is inoperative and when the saw has been energized, either inadvertently or in preparation for a sawing operation. In a sawing operation, as the saw blade is moved through a board being cut, the guard member engages the board and is moved to a retracted unguarding position as the saw blade moves through the board. When the cut through the board has been completed, the saw is removed from the board and the above-mentioned coil spring automatically returns the guard member to its guarding position.
However, just as the guard member can be moved to its unguarding position by a board during a sawing operation, the guard member also can be inadvertently moved to its unguarding position by the operator engaging the guard member with his hand, arm, leg or another part of his body. When this occurs, as noted above, the operator can be seriously injured. Accordingly, a need exists for a device to latch or lock the guard member in its guarding position when the saw is not being used in a sawing operation. The latching device also should be readily releasable by the operator when it is desired to use the saw in a sawing operation, and should automatically relatch the guard member in its guarding position after the sawing operation has been completed. In this connection, a primary purpose of this invention is to provide a releasable latching device for a guard member of a portable hand tool, such as a circular power saw, wherein the latching device has these desirable features. Other applications for the releasable latching device are manifest.